mylist = []

flag = '>>>'

while flag != 'STOP':
    inp = input('?')
    if inp == 'STOP':
        temp = ''
        for index in range(len(mylist)):
            if index > 0:
                temp = temp + str('@')
            temp = temp + str(mylist[index])
        print(temp)
    flag = inp
    mylist.append(inp)
